Ophthalmic camera with adjustable light support



Aug. 9, H. PEARCE OPHTHALMIC CAMERA WITH ADJUSTABLE LIGHT SUPPORT Filed Nov. a, 1945 In 9m f/Aflma E/IRCE gg E Patented Aug. 9, 1949 OPHTHALMIC CAMERA WITH ADJUSTABLE LIGHT SUPPORT Harold Pearce, Ottaw signor to The Home Scientific and Indu (l nt-aria, Canada, a c

a, Ontario, Canada, asr ary Advisory Council for strial Research, Ottawa, orporation of Canada Application November 8, 1945, Serial No. 627,438

1 Claim. 1

This invention relates to photographic apparatus for ophthalmic photography, especially for photographing the cornea of the eye.

Of the many types of cameras previously made none has been really successful for photographing the cornea 0f the eye, although a camera which could be used for this purpose has been needed for a long time. Thus, for example, in the study of riboflavin deficiencies it has been known that the extent of corneal vascularization, i. e. the axis through substantially a 360 arc and also spread of blood vessels in the cornea of the eye, is related to such deficiency. These blood vessels are, however, minute and there has been no way of making an accurate record of them or of changes in their appearance with increasing or decreasing riboflavin deficiency.

Hitherto, the only instrument for examining the cornea has been the slit lamp. This consists of a source of fairly strong steady light formed into a beam of slit form and so directed as to be reflected from the iris out through the cornea in the area to be examined. This area is then viewed under suitable magnification through an appropriate optical instrument. The slit lamp is tiring for the patients eyes because the examination takes some time and the light must remain on throughout. However, the volume of light which can be used without injury to the eye is not great enough to permit a satisfactory photograph to be taken. records of the state of the cornea which could hitherto be made were drawings based on observations by the slip lamp. This unsatisfactory situation is shown by the fact that such drawings form the only illustrations of corneal vascularization in a number of recent articles on ribofiavin deficiency by Drs. Sydenstrecker, Sebrell, Clelckley and Kruse, who are outstanding investigators in this field; see, for example, Journal of the American Medical Association, vol. 114, pages 2437-2445, June 22, 1940.

The apparatus of the present invention has been designed particularly to provide photographic records of eye conditions and especially of corneal blood vessel conditions.

The apparatus according to the invention for ophthalmic photography comprises a source of light which is adapted upon energization to produce a hash light of intensity equivalent to energy of not less than about 1,000,000 watts and a duration of not more than 1/10000 of a second. Preferably the intensity is equivalent to energy of about 2,000,000 watts and the duration is about 1/ 15000 of a second or less. Means are provided for energizing and de-energizing this source of.

Consequently, the only 2 light and a pilot light of relatively low intensity is mounted co-axially with this source. The apparatus includes a camera, a support for the head of the person whose eye is to be photographed, means for adjusting this support to bring the eye onto the axis of the camera, and means for focusing the camera on the part of the eye to be photographed. The light source and pilot light are supported for adjustment around the camera for adjustment in a plane containing the camera aXis and perpendicular to the plane of arcuate adjustment. The pilot light gives the required light for focusing and may be adjusted by the operator in such a way that there is no total reflection along the camera axis from the eye to' be photographed. Since the pilot light is mounted co-axially with the light source, the result of such adjustment is that total reflection along the camera axis of the light of the high intensity flash is entirely avoided.

The invention will be described in more detail by reference to the attached drawing which illustrates a form thereof adpated especially for ophthalmic photography.

In the drawings,

Figure 1 is a general side elevation of the camera set up for operation with a subject ready to be photographed, and

Figure 2 is a partial perspective view with parts broken away.

The camera used in the apparatus of the invention may be of any suitable type. As shown in Figure 2 it comprises the usual casing H, extensible bellows 2 and a lens and diaphragm holding casing 3 at the outer end of the bellows. On top of the casing l is a focusing hood 4 and at the rear of the casing is a suitable holder 5 for light sensitive material, which in the case illustrated is in the form of a film. The camera is supported from a base 6 in such a way that it may be adjusted transversely to the camera axis through the knob l, verticall through the knob 8, and longitudinally of such axis through the knob 9, each of these knobs operating appropriate rack and pinion mechanism, and suitable known means being provided for securing the parts in adjusted position.

Opposite the camera is a support [0 for the head of the person whose eye is to be photographed, this support being adjustable longitudinally oi the camera axis through the clamping screw II and vertically through the knob l2. It is provided with a holder i2a pivoted at I 21),

3 Whose angular positions may be adjusted through a knob I20 to ensure that the head of the person to be photographed, whose forehead is pressed against it, will be held vertical. Because of the provision of the adjustable camera support and head support, the position of the eye to be photo graphe dcan be adjusted with relation to the camera onthe basis of the first subject to be photographed, and succeeding subjects may then be photographed with either no further adjustment, or only minor adjustments necessitated by slight differences in relative positions of the eyes in the heads.

Supported for adjustment apound the camera axis (indicated by the horizontal broken line in Figure 1) through a full circle, that is, through a 360 arc, and also in a plane perpendicular to that circle and containing the camera axis is a casing l3 containing a high intensity light source diagrammatically indicated in dotted lines "at TBc and a co-axially mounted 10W intensity pilot light diagrammatically indicated dotted lines attiSd. QQne type of high intensity light source which has been successfully used in practice is that model of the well-known Kodak Kodatron equipment made by the Eastman Kodak Compa "y whichabsorbs about 2,000,000'watts of energy and has a flash of a duration of about /300Qo joif' a second. "Light sources giving a flash of a duration of about of a second have also been successfully used in practice. The pilot light l3 d may be an ordinary low powerbulb. Y The casing I3 as a 'forwardcylindrical part 13a which encloses'both the light source I 30 and the pilot light 13d and h olds s eer more condensing lenses 131) whichzfor'm beams of thelight produced by both the sou ce 130 arid the pilot iSd. I

The casing lt is'supported from the camera casing I by an arm E5, the horizontal branch l5a 'of'which passesthrough a bracket l4 on the casing l3 and the verticalarm' I5b of which passes through a bracket 5/ The bracket Misslidabl'e and rotatable on the branch a of the arm' and may be'flxed in adjusted position bya thumbscrew 11, while the branch I51) of the arm is slidable and rotatable in the bracket l6 and may be fixed in adjusted position in that bracket by a thumbscrew l8.

The bracket is is carried by an extension [9 of a ring 20, which is supported for rotation between :1

two fixed rings 2| and 22, which have square openings corresponding to the dimensions of the casing I so that the whole light assembly may be slipped onto the casing where it is secured in position against the block 23 on the casing by a bolt having a knurled knob 23a. The rings 2i and 22 are provided with a pair of registering openings through which a pin carried by a knob 24 may pass. The ring is provided, around its periphery, with a number of registering openings, e. g. four, spaced at angles of from each other. To free the ring for rotation the knob 24 is withdrawn towards the rear of the camera, that is, 'towards'the focusing hood 4, and the ring 25.! then rotated until the light source is in the desired position and one of the openings in the ring 28 registers with the pair of openings in the rings 2[ 22. The knob is is then released so that the pin passes through all three openings and secures the parts in adjusted position. One such position is indicated in full lines in Figure 1. The angular position removed from it is indicatedin dotted lines. More pairs of registering openings could of course be provided in the rings 2 t and'ZZ if desired. The casing l3 isth'us uni- 4 versally adjustable with respect to the camera casing l.

The apparatus may be used to photograph either the whole eye or approximately one quadrant of the eye. In Figure 1 it is assumed that the lower quadrant of the eye is to be photographed. For this purpose the subject rests his head on'the support wand looks at a spot in the centre of lens I31), the casing [3 being in this case in its uppermost position as shown in full lines in the drawings. The pilot light is turned on by some appropriate switch not shown and, while the operator looks through the focusing hood 4 onto an appropriate ground glass screen, appropriate adjustments of the camera and support are made to bring the eye of the person to be photographed onto the axis of the camera. The support II] is then moved toward or away from the camera, and the angle of the casing 13, whose longitudinal axis coincides with the beams from the source I30 in pilot light l3c Z, is adjusted until total reflection' of the light from the pilot light along the camera axis is avoided. The operator can obs erv e when the adjustment is properly made because at that time he will see in the viewing screen no total reflection by the eye to be photographed of the beam from the pilot light. the'adjustment has been completed the photograph is taken by operating the camera shutter mechanism, for example, through a shutter tripping lever 5. This mechanism carries suitable means for energizing the light source the shutter of the camera opens and ale-energizing it as the shutter closes. The interval between energization and de-energization is relatively unimportant with the type'of light source referred to above, provided it does not exceed about 10 seconds, because that interval has nothing to do with the duration ,of'the flash from the light i source. is necessary simply that the source be s g r e o e i a built u a a n f r t e fl shee l m ev iff e forms of n r ze i r ner ze qn eans ma be satisfactory. The form shown and described in shn P t n N 9 1 7 mo e 19 3 bf which the present application a conti ua; tion inpartfis one which has been used suc ssfully in practice.

What I l n? .15

p h lmic photo r ph a pa a com rist s' a sin e 8? 9 light a apted pon ener izar i nto P e a h f li t o an intensity q i al nt s n r of ea ess an b ut 1.000.- 9. We ta d du at on o n t o h n about one ten-thousandth of a second, means for en: ieme a d deener i m sa d sour e. a pilot of relatively very low intensity mounted C0? axially with said source, means for forming beams of the light from said source and from said pilot light, a camera, a support for the head of the per.- son whose eye is to be photographed, means for adjusting said support to bring the eye onto the axis of the camera, means tor focusing the camera on the part of the eye to be photographed, and means mounted on the camera for supporting said light so e d pilot light for adjustment around the camera axis through substantial y a 360 arc and also for adjustment in a plane containing the camera axis and perpendicular to the plane of said arcuate adjustment, whereby the beam from id light r e m y be so i ec ed a t e eye as to avoid total reflection along the camera axis. AR LD EARC flis e nee e1 fiv rwins P e) REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Number Name Date Grier Mar. 3 1942 Curran Mar. 16, 1943 Osterberg et a1 May 23, 1944 FOREIGN PATENTS Country Date France Sept. 25, 1933 Great Britain June 11, 1940 

